Minakata K, Asano M, Sato T, Harada N
Hoppe Seylers Z Physiol Chem. 1982 May;363(5):493-8. doi: 10.1515/bchm2.1982.363.1.493.
A new proteinase inhibitor has recently been found in human serum or plasma which specifically inhibits cysteine proteinases such as ficin, papain, bromelain and cathepsin B. However, serum contains alpha 2-macroglobulin which also inhibits these cysteine proteinases and, consequently, interferes with the assay of the new alpha-cysteine proteinase inhibitor. Therefore, assay of the inhibitor in serum has not been established previously. In the present method, the alpha 2-macroglobulin is inactivated by preincubating the serum in methylamine solution at 55 degrees C, while the alpha-cysteine proteinase inhibitor retains its activity. The inhibitory power against cysteine proteinases is found to be due mainly to this protein in human serum. This inhibitor is also found in mammals such as cows, pigs and rats. Vitamin E deficient rats show a very high inhibitor level. Therefore, the present method will enable us to investigate the relation between diseases and the activity of the alpha-cysteine proteinase inhibitor. Also, this method is simple and inexpensive. The necessary amount of serum is only 10 microliter.
最近在人血清或血浆中发现了一种新的蛋白酶抑制剂，它能特异性抑制半胱氨酸蛋白酶，如无花果蛋白酶、木瓜蛋白酶、菠萝蛋白酶和组织蛋白酶B。然而，血清中含有α2-巨球蛋白，它也能抑制这些半胱氨酸蛋白酶，因此会干扰新的α-半胱氨酸蛋白酶抑制剂的测定。所以，此前尚未建立血清中该抑制剂的测定方法。在本方法中，通过将血清在55℃的甲胺溶液中预孵育来使α2-巨球蛋白失活，而α-半胱氨酸蛋白酶抑制剂则保留其活性。发现人血清中对半胱氨酸蛋白酶的抑制能力主要归因于这种蛋白质。在牛、猪和大鼠等哺乳动物中也发现了这种抑制剂。维生素E缺乏的大鼠显示出非常高的抑制剂水平。因此，本方法将使我们能够研究疾病与α-半胱氨酸蛋白酶抑制剂活性之间的关系。此外，该方法简单且成本低廉。所需血清量仅为10微升。
